What type Plywood to use?

[mick11]

There are so many types of plywood ratings out there. I'm no expert, so when I went to the lumber yard and said I needed plywood, they had a list and I didn't know what to purchase.

What should you use to make plywood tanks?

Thanks for any advise.

Mick

 

[IITUFFTOBEATII]

i would use ainsworth form ply. no knots or other inconsistencies like warping to deal with. depending on what you want for color you dont have to refinish it, it is already stained. your lumber yard will prob have to order it, and its $$$. but by buying better materials you can save yourself $ and headaches later in your build.

 

[nuggets]

or you can go with double sided oak or walnut 4x8 sheets are about 50 to 60 bucks and they are oh so nice no warping

 

[CJH]

What should you use to make plywood tanks?

I have a few thoughts. I first want to comment on the use of form plywoods as mentioned by the previous poster. I think some of these have a lot of potential as they tend to have extremely smooth surfaces which can allow for more efficient use of whatever sealer you might use. They also allow for sealers to form a more continuous cross linked layer since there are not so many tiny voids to fill.

But on that same note, I also want to warn that some form plywoods are treated with oil or even have a layer of phenolic resin on them. They are designed to release from cured concrete so very few of the sealers one might use on a plywood tank will adhere to them. There are many types of form plywoods and it can be very hard to keep them straight. There are some that will absolutely not work, others would be about ideal.

With that said, I think I would recommend a type of plywood that is sometimes used for concrete form work. It is Medium Density Overlay, aka MDO. It has a layer of resin impregnated paper on both surfaces and also uses a water resistant glue to laminate the layers.

I know I mentioned avoiding form plywoods with resin layers above, but MDO was designed for outdoor sign work and is designed to take paint. It is also relatively inexpensive, or at least it was the last time I priced it. I have not used it for a tank but have heard of others doing so.

So MDO if you plan to use epoxy, epoxy paint or possibly vinyl ester resin.

If you plan to use a waxed or unwaxed polyester I would be concerned with adhesion as I think these resins actually need a bit of surface area to bite into for that ever so important first coat. I have read some boat building forums where it has been mentioned that polyester resin does not stick well to plywood.

I have used waxed polyester on AC plywood but scuffed it up with coarse sandpaper first and I did not notice any adhesion issues.

 

[mick11]

I plan to use epoxy resin with a fiberglass cloth.

I do a lot of composite work in the aviation business, so I have that part covered.

I appreciate the help on selecting the plywood.

 

[Issack]

Any A/C grade plywood will do fine. I used maple ply on mine. Works just fine.

 

[cjohll]

with the right epoxy fiberglass mix you could make a cardboard box into an aquarium.

 

[sweetseahorse]

i know this might sound dumb but can you really do this? I was just thinking of ways to make a diy tank cheaper. Cardboard is dirt cheap. The right bracing... could be lie those japanese paper walls you see... that could be kinda cool.